In today's world, and for the forseeable future, energy conservation is and will continue to be a matter of paramount importance. As is well known, furnaces and the like lose significant amounts of heat up the chimney. This is particularly true with respect to fireplaces in residences where a great deal of the heat energy from the fire and the warm air in the residence is wastefully expelled up the chimney. This results in the fact that a merrily blazing fire in a conventional fireplace may contribute very little net heat input into the residence and in fact may result in a net heat loss to the residence, depending on the outside air temperature.
Accordingly, one of the objects of the present is to provide a heat economizer which will extract a great deal of the heat otherwise lost up a fireplace chimney or the like, making it available for use in the building in which the economizer is located.
Other objects of the present invention are to provide an economizer which is resistant to leakage of the flue gasses therefrom, which is structurally strong, yet relatively light in weight, and which has an increased fire safety. These objects are at least partially achieved by the following aspects of the present invention. First the upper and lower ends of the flue tubes are welded to upper and lower tube sheets to provide a structurally strong, flue gas leak resistant economizer. Second, the structurally connected flue tubes and tube sheets support the inner and outer casings and the layer of non-flammable insulation sandwiched therebetween, enabling the inner and outer casings to be made from very light, thin sheet metal since they are supported by the tube sheets and flue tubes. Third, the layer of insulation and the inner and outer metal casings significantly enhance the fire safety of the economizer.
Another object of the present invention is to provide a strong, modular heat economizer which is easily transported, handled and installed, which is easily removed for repair or maintenance, and which can replace at least a portion of a conventional chimney. This object is at least partially achieved by the construction discussed above and by providing outwardly extending flanges on the tube sheets which enable the economizer to be releaseably held in place by any conventional fastener means, such as nuts and bolts. In addition, an access door may be provided in the flue or chimney above the economizer, and/or in the side wall of the building in which the economizer is installed in order to provide access to the economizer for inspection, maintenance, repair, installation, or removal.
Another object of the present invention is to provide a heat economizer which is resistant to leakage of flue gases caused by the thermal expansion and contraction of the economizer during use. This object is at least partially achieved by providing expansion joints in the inner and outer casings to help to prevent warping of the economizer and to help to prevent cracking of the welds between the flue tubes and the tube sheets.
Other objects of the present invention are to provide a heat economizer which, in effect, consumes the products of combustion which are likely to condense in the economizer, in the flue or chimney above the economizer, and on the inside of the precipitation cap covering the top of the flue or chimney; in order to reduce fire hazards, to maintain the flue tubes unobstructed, and to reduce or eliminate the unsightly and unsafe leakage of such condensation products from the flue or chimney above the economizer and from the precipitation cap. These objects are at least partially achieved by the following aspects of the present invention. First, an economizer thermostat is connected to the flue tubes and to the means for forcing air through the economizer in order to maintain the temperature of the flue tubes at least about 350.degree. F., a temperature sufficient to prevent condensation of the products of combustion, and particularly creosote, within the flue tubes. Second, the tops of the flue tubes are welded flush with the top of the upper tube sheet, or recessed below said top, and encircled by an upstanding flange on the top of the upper tube sheet to encourage the condensation products within the flue or chimney above the economizer, and from the precipitation cap, to drain into the flue tubes where they can be evaporated by the hot combustion gases or consumed by the fire in the fireplace, furnace, or wood stove, for example. Third, the precipitation cap may include a downwardly projecting precipitation director to encourage condensation products in the cap to drain into the economizer where they can be disposed of as mentioned above.
Another object is to provide a heat economizer which efficiently exchanges the heat from the flue tubes to the air circulated within the inner casing. This object is at least partially achieved by providing baffles within the inner casing to direct the air in a tortuous path about the flue tubes and by circulating the air in the economizer in a downwardly direction generally counter to upwardly flowing combustion gases within the flue tubes.
Another object is to provide a modular water heater which also replaces a portion of the chimney above the source of combustion heat and which may be easily coupled to the economizer.
The foregoing objects, features, and advantages of the present invention which have been mentioned are by no means to be considered exhaustive. It will be appreciated that further objects, features, advantages and characteristics of the present invention will be apparent from the following more detailed description of the preferred embodiments thereof.